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Inne
2,7-disubstituted proton sponges as borderline systems for investigating barrier-free intramolecular hydrogen bonds. Protonated 2,7-bis(trimethylsilyl)- and 2,7-di(hydroxymethyl)-1,8-bis(dimethylamino)naphthalenes.
Autorzy
Rok wydania
2008
Czasopismo
Numer woluminu
64
Strony
6209-6214
DOI
10.1016/j.tet.2008.05.00
Kolekcja
Język
Angielski
Typ publikacji
Artykuł
Protonated 2,7-bis(trimethylsilyl)- and 2,7-di(hydroxymethyl)-1,8-bis(dimethylamino)naphthalenes have been prepared and studied by a combination of X-ray crystallography at room and low temperatures, IR and NMR spectroscopic techniques in conjunction with quantum-chemical calculations. It was demonstrated that the intramolecular [NHN] + hydrogen bond in the 2,7-bis(trimethylsilyl) system, being sterically compressed, is the shortest among all known aromatic diamine systems. Nevertheless, as it is evidenced by the primary 1 H/ 2 H isotope effect, IR spectra and MP2 calculations, a double minimum potential for the proton motion still exists with a very low barrier estimated to be about 0.7kcal/mol. An influence of a counter-anion on the NH proton involving the spatially hindered H-bond is also considered.
Słowa kluczowe
Sterically modified proton sponges, Intramolecular hydrogen bond, Proton transfer, Molecular structure
Adres publiczny
https://doi.org/ 10.1016/j.tet.2008.05.00
Strona internetowa wydawcy
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